Add custom useragent for mangamate

[ZerOri]

Source name

mangamate

Source language

Japanese

Describe your suggested feature

Use mobile useragent to bypass cf in webview. Please add custom useragent function to the plugin

Other details

Unable to bypass cf protection with desktop useragent

Acknowledgements

• [X] I have searched the existing issues and this is a new ticket, NOT a duplicate or related to another open or closed issue.
• [X] I have written a short but informative title.
• [X] If this is an issue with the app itself, I should be opening an issue in the app repository.
• [X] I have updated the app to version 0.15.3.
• [X] I will fill out all of the requested information in this form.